Simultaneous updates to the modification time attribute of a shared file in a cluster having a server and client nodes

A method for updating a modification time field of a file in a cluster system having a plurality of client nodes, comprising the steps of:

• maintaining, at each of the client nodes, a copy of the modification time specified in the modification time field;
• concurrently updating, by at least some of the clients nodes, their respective modification time copy,
• when a client requests to read the modification time field of the file, reconciling each copy with one another, and
• when an explicit user-issued command to set the modification time superseding all others is issued by a client node, granting an exclusive-write lock on the modification time field.

A method for updating the modification time of files in a cluster system having a plurality of clients which can access and simultaneously update a modification time field of a shared file stored on a commonly accessible storage device accessed under control of a server, comprising the steps of:

• maintaining at a local cache in each of the clients, a copy of the modification time,
• when one of the clients requests to explicitly set the modification time, granting, by the server, a write lock to the one of the clients on the modification time field of the shared file,
• whenever one of the clients requests to read the modification time reconciling the locally cached copies of the modification time by sending the copy of the modification time maintained at each client to the server;
• causing the server to select the most recent modification time from the modification time copies;
• and, writing the most recent modification time in the modification time field of the shared file.

A system for maintaining the modification time of files in a cluster system, said cluster system comprising client and at least one server node, and having a plurality of clients which can access a modification time field of a shared file, comprising:

• a communication network;
• a plurality of nodes coupled to the communication network, each of the nodes including a attribute cache for storing a copy of a modification time of the shared file and means for accessing the local copy of the modification time, wherein, each of the nodes can simultaneously update their local copy of the modification time.
• at least one of the nodes being configured as a server and being connected to a disk instantiating a filesystem including the shared file and comprising means for reconciling the local copies whenever one of the clients requests to read the modification time;
• and,
• a lock manager coupled to each of the nodes the lock manager including means for granting an exclusive write lock to one of the nodes on the modification time field of the shared file, when the one of the nodes requests to explicitly set the modification time.